The present invention concerns a machine for shotpeening helical compression springs.
The machines most commonly employed for shotpeening helical compression springs, mainly automotive suspension springs, throughout the world today use standard shot-impelling rotors.
The springs are mostly conveyed into and through the peening section by a chain that thrusts or drags them forward horizontally while they rest over two cylinders that rotate in the same direction.
The springs rotate along with the cylinders subject to friction, and the intention is uniform bombardment of the total circumference.
There is a drawback to this system, however. If the processing parameters, especially the ratios of the speeds of the chain and cylinder to the outside diameter of the springs are not absolutely precise, the springs will tend to slip back and forth more or less extensively over the cylinders.
This slippage leads in conjunction with the extreme conditions of pressure and temperature at the linear contact between the springs and the cylinders to what are called lines of friction. Lines of friction can in many cases considerably curtail the life of the component.
Further problems can occur in conveying specially shaped springs when their windings differ considerably in diameter or deviate extensively from the cylinders.